Anisotropic wetting phenomenon on structured solid surfaces is of both fundamental and technological interest. Surfaces with controlled anisotropic wetting have the advantages of confining liquid flow to a desired direction, with potential applications in microfluidic devices, evaporation-driven formation of patterns, and easy-clean coatings. Anisotropic wetting has been observed in nature and biomimetic structures have been fabricated with various techniques including aligned carbon nanotubes (CNT). Anisotropic wetting behavior is also observed on one-dimensional (1D) patterned surfaces achieved either through chemical patterning or surface roughness. Drainage enhancement has been reported with the aid of wetting anisotropy on etched 1D aluminum surfaces. However, most of the literature on anisotropic wetting behavior is concerned with relatively low degrees of anisotropy on surfaces with micrometer-scale parallel grooves. There have been relatively few papers reporting strong anisotropic wetting behavior, the variation of the wetting behavior over large material variations, or the evaporation dynamics of anisotropic liquid droplets. There have been reports of modifying the wetting behavior on isotropic surfaces, but it remains a challenge to adjust anisotropic wetting properties with simple, effective and low cost techniques.
Hence, there is a need to develop a simple, effective, and low cost method of controlling anisotropic wetting behavior of a surface.